I used a simpler method from the comfort of my armchair.
Put a steel T bracket on the end of a bit of 25 x 25 mm pine and drilled the central hole out for a camera screw.
I then mounted the assembly onto the tribrach and tripod from a laser level kit.
The window in my living room has a single central divider so I pointed the camera at that with the zoom set to wide angle.
The camera was slid backwards and forwards until the background remained stationary relative to the window divider when the tribrach was rotated.
I then marked the wooden strip to record the position and wrote on the focal length.
Repeat every 50 mm until full zoom is reached.
I then had a simple mount for single-row panos which I could set to suit the required focal length.
The screws on the tribrach enable me to set the axis of rotation to vertical with a good degree of accuracy.
For panos sightly above or below the horizontal plane the wooden strip can be canted up or down before clamping.
Don't have a photo of the actual setup but it looked like this (a later version with a stiffer mount) http://www.flickr.com/photos/73571158@N00/2995521498/in/set-72157623635436569